One type of fire control mechanism commonly used in semiautomatic hand-guns includes a hammer which is pivotable from a rearward cocked position to a forward position for impacting the firing pin. A sear releasably retains the hammer in its cocked position with the hammer spring or main spring in compression. When the trigger is actuated, the sear is moved to release the hammer that is moved by the stored energy of the main spring, to strike the firing pin which is thereby driven forward to fire a chambered round. The principal drawback of this type of mechanism is that it includes numerous parts and is relatively complex and expensive to manufacture.
Another common configuration is disclosed in U.S. Pat. No. 3,857,325 to Thomas wherein a striker type firing pin is utilized in lieu of a pivotable hammer. Upon actuation of the trigger, a trigger bar operated sear engages a projection that extends from the firing pin and moves the firing pin rearward, thereby to compress a firing pin spring. When the trigger is moved a predetermined distance rearward, the sear will be moved to release the firing pin projection whereby the firing pin spring will drive the firing pin in a forward direction with sufficient force to fire a chambered round. This mechanism has at least one principal disadvantage in that there is no provision for disconnecting the sear from the trigger to allow the sear to move independently back into the path of the firing pin during the recoil of the slide. The absence of this feature makes for a gun having a relatively low rate of fire. In addition, this mechanism may be difficult to manufacture and its components subject to fatigue and failure with extensive usage.
Other configurations which utilize firing pin striker mechanisms include those disclosed in U.S. Pat. Nos. 4,539,889; 4,825,744 and 4,893,546 issued to Glock. In all but one of the configurations of the above referenced patents, which discloses a hammer for engaging the firing pin, an abutment is provided to alternately engage and disengage the nose of a firing pin. When the trigger is actuated, the abutment engages the downwardly depending nose of the firing pin and moves the same rearwardly until the nose and the abutment have reached a predetermined position. With the firing pin at that position, the spring will have been compressed and various control or camming means are disclosed for moving the abutment out of the path of the firing pin nose whereby the firing pin spring will impel the firing pin with sufficient force to fire a chambered round.
One of the principal characteristics of such prior art pistols is that, even before actuation of the trigger, the firing pin spring is quite strongly preloaded or tensioned in an intermediate or semi-cocked position which operates more in the manner of a single action firing mechanism than a classic double action mechanism.
Another characteristic of certain currently available pistols is that the firing mechanism includes a spring to assist in the rearward or firing movement of the trigger in lieu of the more conventional type trigger spring that opposes the trigger pull. That spring aids the trigger pull and thus assists in the compression of the main firing pin spring so that the pistols will have a relatively light trigger pull over a substantial portion of the length of the trigger stroke.
In each of the embodiments disclosed in the above referenced patents, upon recoil of the slide after a round has been fired, a leaf spring is caused to move laterally to enable the abutment portion of the firing mechanism to be moved upwardly, after the firing pin has been released when the gun is fired. In that upward position, as the firing pin is carried forwardly by the slide, the abutment will be disposed to be reengaged by the nose of the firing pin. With reengagement of the two parts, the abutment will be carried forwardly until the leaf spring snaps back laterally to its initial position and the control surface on the leaf spring will be repositioned ready to cam the abutment downwardly in the next firing cycle. After the first round has been fired, the trigger can be restrained by the shooter against moving forwardly to its original starting point at which it was located prior to firing the first round.
Such pistols can therefore be said to have two different trigger stroke lengths, i.e., the first one of approximately the same length as is conventional and subsequent strokes which are substantially shorter than the conventional stroke. In the use of the shorter stroke, there may be a tendency for some shooters, not fully familiar with that trigger feature, to fire the pistol when not really intending to do so. Furthermore, as the firing pin is carried forwardly by slide after the gun has been fired, when the nose reengages the abutment, the firing pin will be partially cocked and such subsequent strokes would be more in the nature of a single action stroke. The effect is a reduction in the momentum of the forwardly moving slide which substantially lessens the kinetic energy available to return the slide fully to its forward position. Guns of this type have been found to have a higher incidence of the slide failing to close fully during the recoil cycle. With this type of firing mechanism, moreover, the repeated flexing of the leaf spring and forceful impacting of the nose on the abutment will have a tendency to cause excessive wear of these components.
It is the principal object of this invention to provide an improved double action semiautomatic handgun having a striker type firing mechanism which overcomes the drawbacks of similar types of handguns heretofore available.
It is also a primary object of this invention to provide a double action firing mechanism of the above type that provides for application to the trigger of constant force and stroke length for each and every round fired.
It is an additional object of this invention to provide a handgun fire control mechanism of simple and compact construction that is lightweight and relatively inexpensive to manufacture while being safe and reliable in operation.
Another object of this invention is to provide a handgun fire control mechanism which utilizes essentially all of the force of the recoil spring to recycle the slide.
Still another object of this invention is to provide a fire control mechanism of the above type in essentially all the energy of the slide is used to reset the firing mechanism.
According to this invention, a double-action striker type firing mechanism for a semiautomatic pistol includes a trigger bar which pivots a sear lever rearwardly from an initial forward position that is biased toward that forward position by a sear spring. Thus, tensioning of the sear spring as well as compressing a firing pin spring is required to cock the striker and upon the sear achieving predetermined angular and translatory motion from its forward position, the sear is adapted to release the firing pin at a point at which sufficient potential energy has been imparted to the firing pin to fire a chambered round. On recoil of the slide, the sear and firing mechanism are adapted to be fully repositioned for the next cycle by movement in parallel planes.